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Magnetoresistance in oxydized Ni nanocontacts

D. Jacob, J. Fernández-Rossier, J. J. Palacios. Department of Applied Physics, U. Alicante, 03690 SPAIN. Magnetoresistance in oxydized Ni nanocontacts. Ni. Ni. Ni. Ni. Oxygen. Small Magnetoresistance. Large Magnetoresistance >90%. D. Jacob, JFR, J. J. Palacios

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Magnetoresistance in oxydized Ni nanocontacts

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  1. D. Jacob, J. Fernández-Rossier, J. J. Palacios Department of Applied Physics, U. Alicante, 03690 SPAIN Magnetoresistance in oxydized Ni nanocontacts Ni Ni Ni Ni Oxygen Small Magnetoresistance Large Magnetoresistance >90% D. Jacob, JFR, J. J. Palacios PRB 71, R220403 (2005) D. Jacob, JFR, J. J. Palacios Cond-mat, 0603359 A single atom can make a difference www.ua.es/personal/jfrossier/ V22.00002

  2. Motivation I: MR EXPERIMENT:Small BMR in Ni80Fe20 K. Bolotin et al. Nano Lett.,6(1), 123, (06) D. Jacob, JFR; J. J. Palacios PRB71, R220403 (2005) THEORY: Small BMR in PURE Ni nanocontacts

  3. Ni Ni Oxigen Motivation II: Motivation III: Probing Ni-O-Ni chemical bond Bulk NiO=AF Mott Insulator

  4. Electronic Structure calculation Ni Ni Oxygen Tight Binding B3LYP Free Bands • Parametrization 3D • Charge neutrality • Bulk NiO: • AF OK • Insulator OK • GAP Ok • Magnetic Moment OK • No Self Interaction: OK LDA • NiO: FM, no gap, no Mott Hubbard • Self Interaction

  5. Ni Ni Oxigen Electronic Structure calculation Tight Binding B3LYP Free Bands • Parametrization 3D • Charge neutrality • Bulk NiO: • AF OK • Insulator OK • GAP Ok • Magnetic Moment OK • No Self Interaction: OK LDA • NiO: FM, no gap, no Mott Hubbard • Self Interaction

  6. Electronic Structure: Infinite chains CRYSTAL03 B3LYP, NiO FM chain FERROMAGNETIC HALF METAL 2 Doubly degenerate E1 band Ni(+)O(-)

  7. Electronic Structure: Infinite chains CRYSTAL03 B3LYP, NiO AF chain ANTIFERROMAGNETIC INSULATING Ni(+)O(-)

  8.  Ni Ni Oxigen Electronic structure: nanocontact • Infinite system without translational invariance • Cluster Embeddedcalculation • Cluster in DFT aprox, LCAO, GAUSSIAN03 • Leads: semiempirical TB, Bethe lattice

  9. Nanocontacts: Single Oxygen Bridge High MR

  10. Electronic Structure: Infinite chains FERROMAGNETIC INSULATING WARNING: Small MR

  11. Insulating SINGLE ATOM SPIN VALVE Ni Ni Ni Conducting

  12. Conclusions • A single atom can make a difference: Ni-O-Ni can have large MR • A single atom can makes a difference:SINGLE ATOM SPIN VALVE • Atomic sized contacts: PROBING TM-O-TM chemical bonding www.ua.es/personal/jfrossier Jfrossier@ua.es

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